This invention relates to microfabricated incandescent lamps and, in particular, to methods for fabricating arrays of microminiature incandescent lamps, to the arrays so fabricated and to circuitry for operating arrays of microminiature incandescent lamps.
It is desirable to use microminiature incandescent lamps to form an array of micromachined incandescent filaments for use in the manufacture of flat panel display assemblies. In many military and civilian applications (e.g., portable computers, automobiles and aircrafts) a need exists for a flat, inexpensive, lightweight electronic display for images and digital information. Cathode ray tubes (CRTS) are too large and heavy for use in these environments. Known conventional flat panel alternatives have significant drawbacks. Liquid crystal displays (LCDs) suffer from slow response, narrow viewing angle, difficult viewing without backlighting, and extremely high cost. When backlighting is used with an LCD, the backlit LCDs waste most of the optical power from their lamps because their operation is based on blocking the light of the pixels that are not required to be lit. Electroluminescent displays are inefficient. Plasma displays require high voltage circuitry and are inefficient. Light emitting diodes (LEDs) have not been produced with blue color at a reasonable cost and efficiency. Also, the best blue light producing LEDs currently can not be fabricated on the same substrate material as the red and green LEDs. This makes the process for manufacturing an array of red green and blue LEDs difficult and costly.
Therefore, there is a need for a technology which can give high brightness over the full color spectrum, which has a relatively fast response, which can operate at moderate voltage levels, and which has high efficiency, all at a low production cost. Applicant recognized that microminiature incandescent lamps is such a technology and that it may be used to produce display panels which can replace CRTs and known conventional flat-panels in many applications.